javascript 解惑

var json = {
    "func":function () {
        return this;
    }
};

var value = json["func"]();
alert(value); // [object Object]

var value = json["func"];
alert(value()); // [object Window]

var flag = 0;

if (true) {
    var flag = 1;
}

function func(){
    var flag = 2;
}

alert(flag); // 1